Experimental realization of a semiconducting full Heusler compound: Fe2TiSi

Single-phase films of the full Heusler compound Fe2TiSi have been prepared by magnetron sputtering. The compound is found to be a semiconductor with a gap of 0.4eV. The electrical resistivity has a logarithmic temperature dependence up to room temperature due to Kondo scattering of a dilute free electron gas off superparamagnetic impurities. The origin of the electron gas is extrinsic due to disorder or off-stoichiometry. Density functional theory calculations of the electronic structure are in excellent agreement with electron energy loss, optical, and x-ray absorption experiments. Fe2TiSi may find applications as a thermoelectric material.Comment: 6 pages, 6 figure

Central and peripheral aspects of hypothalamic-pituitary-adrenal (HPA) axis dysfunction

An aberrant regulation of the hypothalamic-pituitary-adrenal (HPA) axis is closely associated with the pathophysiology of affective disorders such as major depression (MD). Accordingly, patients suffering from MD frequently show profound neuroendocrine alterations with hyper- or hypo-cortisolism as a result of a dysregulated stress hormone system. Focussing on this key endophenotype of MD, the ‘stress reactivity’ (SR) mouse model was recently established, consisting of three independent mouse lines, the high (HR), intermediate (IR) and low (LR) stress reactivity line, selectively bred for differences in their corticosterone (CORT) secretion in response to a psychological stressor. Previous studies revealed distinct differences between HR, IR and LR animals regarding sleep architecture, activity rhythms, emotional behaviour, cognition as well as neuroendocrine functions, resembling several endophenotypes observed in depressed patients. In the series of studies presented in this work, we aimed to investigate whether the differences between HR, IR and LR mice were restricted to the peripheral phenomenon of adrenal CORT secretion, or whether these endophenotypes were brought about by an aberrant regulation of upstream control centres of the HPA axis. To this end, we performed experiments investigating all functional levels of HPA axis control, i.e. the adrenals, the pituitary and brain centres known to be involved in the neuroendocrine stress response. Moreover, we assessed the expression of corticosteroid-binding globulin (CBG), which contributes to the transport and delivery of CORT to its target tissues. Finally, we studied HPA axis regulatory mechanisms by means of the combined dexamethasone/corticotropin-releasing hormone (Dex/CRH) test. At the level of the adrenal, we found that pharmacological inhibition of the biosynthesis and secretion of CORT using metyrapone had a significant impact on the stress-coping behaviour of HR, IR and LR animals as determined in the forced swim test (FST). As another peripheral factor influencing the secretion of CORT, we assessed the adrenal sensitivity of the animals to adrenocorticotropic hormone (ACTH) in vivo. After a Dex-mediated inhibition of endogenous ACTH release from the anterior pituitary, LR animals showed a markedly reduced CORT surge compared to HR mice in response to a stimulation of the adrenals with two doses of exogenous ACTH, indicating an enhanced adrenal sensitivity in HR mice and a blunted responsiveness to ACTH in LR mice. In addition, we found significant differences in plasma CBG levels between the three mouse lines (HR>IR>LR), concomitant with differences in free plasma CORT both, basal and in response to 15 min restraint stress (HR>IR>LR). Since only free CORT is biologically active, these results indicate that CBG might play a role in the endophenotypes of the SR mouse lines. At the pituitary level, we detected significantly altered ACTH protein levels (HR>IR≥LR) and proopiomelanocortin mRNA expression (HR>IR>LR), suggesting a differential activation of the anterior pituitary between the three lines, which is in line with the observed differences in stress reactivity. In the brain, we assessed the neuronal activation induced by an acute stressor in regions known to be involved in HPA axis function such as the prefrontal cortex, the basolateral amygdala, the hippocampus and the paraventricular nucleus of the hypothalamus (PVN) using c-fos in-situ hybridisation. Acute stress exposure markedly increased neuronal activation in all investigated brain areas. However, significant differences in the neuronal excitation between the three lines were only detected in the PVN (HR>IR>LR), indicating an altered activation of the animals’ HPA system orchestrated by this nucleus. Finally, we assessed HPA axis regulatory mechanisms by means of the Dex/CRH test. Our results revealed considerable similarities to clinical studies, with HR mice showing signs of Dex non-suppression in addition to an overshooting CORT surge after CRH stimulation, mirroring the HPA axis hyper-active state of patients suffering from the psychotic or melancholic subtype of MD. In contrast, LR animals presented a strong Dex-induced CORT suppression and a blunted response to the CRH stimulation, resembling the situation observed in atypically depressed patients. Strikingly, chronic fluoxetine (Flx) treatment enhanced the negative feedback regulation of the HPA axis in all three lines of the SR mouse model. In particular, the Dex-mediated CORT suppression in HR mice was restored by Flx. Furthermore, Flx affected the stress-coping behaviour of the animals in the FST. Flx induced a reduction in active coping, indicating an attenuation of the hyper-aroused state, particularly in HR mice. Taken together, the series of studies presented here demonstrated that the SR mouse model shows functional alterations on all levels of the HPA axis - peripheral, central and regarding the regulation – similar to the endophenotypes of MD patients, thus revealing a high level of face and construct validity of the model. Hence, the SR mouse model can serve as a valuable tool in the discovery and validation of new drug targets and improve already existing treatments of MD, particularly those targeting the HPA system

Dendritic Morphology of Hippocampal and Amygdalar Neurons in Adolescent Mice Is Resilient to Genetic Differences in Stress Reactivity

Many studies have shown that chronic stress or corticosterone over-exposure in rodents leads to extensive dendritic remodeling, particularly of principal neurons in the CA3 hippocampal area and the basolateral amygdala. We here investigated to what extent genetic predisposition of mice to high versus low stress reactivity, achieved through selective breeding of CD-1 mice, is also associated with structural plasticity in Golgi-stained neurons. Earlier, it was shown that the highly stress reactive (HR) compared to the intermediate (IR) and low (LR) stress reactive mice line presents a phenotype, with respect to neuroendocrine parameters, sleep architecture, emotional behavior and cognition, that recapitulates some of the features observed in patients suffering from major depression. In late adolescent males of the HR, IR, and LR mouse lines, we observed no significant differences in total dendritic length, number of branch points and branch tips, summated tip order, number of primary dendrites or dendritic complexity of either CA3 pyramidal neurons (apical as well as basal dendrites) or principal neurons in the basolateral amygdala. Apical dendrites of CA1 pyramidal neurons were also unaffected by the differences in stress reactivity of the animals; marginally higher length and complexity of the basal dendrites were found in LR compared to IR but not HR mice. In the same CA1 pyramidal neurons, spine density of distal apical tertiary dendrites was significantly higher in LR compared to IR or HR animals. We tentatively conclude that the dendritic complexity of principal hippocampal and amygdala neurons is remarkably stable in the light of a genetic predisposition to high versus low stress reactivity, while spine density seems more plastic. The latter possibly contributes to the behavioral phenotype of LR versus HR animals

Correction to: Solving patients with rare diseases through programmatic reanalysis of genome-phenome data

In the original publication of the article, consortium author lists were missing in the articl

Solving patients with rare diseases through programmatic reanalysis of genome-phenome data.

Funder: EC | EC Seventh Framework Programm | FP7 Health (FP7-HEALTH - Specific Programme "Cooperation": Health); doi: https://doi.org/10.13039/100011272; Grant(s): 305444, 305444Funder: Ministerio de Economía y Competitividad (Ministry of Economy and Competitiveness); doi: https://doi.org/10.13039/501100003329Funder: Generalitat de Catalunya (Government of Catalonia); doi: https://doi.org/10.13039/501100002809Funder: EC | European Regional Development Fund (Europski Fond za Regionalni Razvoj); doi: https://doi.org/10.13039/501100008530Funder: Instituto Nacional de Bioinformática ELIXIR Implementation Studies Centro de Excelencia Severo OchoaFunder: EC | EC Seventh Framework Programm | FP7 Health (FP7-HEALTH - Specific Programme "Cooperation": Health)Reanalysis of inconclusive exome/genome sequencing data increases the diagnosis yield of patients with rare diseases. However, the cost and efforts required for reanalysis prevent its routine implementation in research and clinical environments. The Solve-RD project aims to reveal the molecular causes underlying undiagnosed rare diseases. One of the goals is to implement innovative approaches to reanalyse the exomes and genomes from thousands of well-studied undiagnosed cases. The raw genomic data is submitted to Solve-RD through the RD-Connect Genome-Phenome Analysis Platform (GPAP) together with standardised phenotypic and pedigree data. We have developed a programmatic workflow to reanalyse genome-phenome data. It uses the RD-Connect GPAP's Application Programming Interface (API) and relies on the big-data technologies upon which the system is built. We have applied the workflow to prioritise rare known pathogenic variants from 4411 undiagnosed cases. The queries returned an average of 1.45 variants per case, which first were evaluated in bulk by a panel of disease experts and afterwards specifically by the submitter of each case. A total of 120 index cases (21.2% of prioritised cases, 2.7% of all exome/genome-negative samples) have already been solved, with others being under investigation. The implementation of solutions as the one described here provide the technical framework to enable periodic case-level data re-evaluation in clinical settings, as recommended by the American College of Medical Genetics

Silicon oxide nanolayers for soft X-ray optics produced by plasma enhanced CVD

Hamelmann F, Aschentrup A, Schmalhorst J-M, et al. Silicon oxide nanolayers for soft X-ray optics produced by plasma enhanced CVD. JOURNAL DE PHYSIQUE IV. 2001;11(PR3):431-436.We have studied the suitability of Plasma Enhanced Chemical Vapor Deposition (PECVD) to produce ultrasmooth silicon oxide layers ranging in thickness from some nanometers to some 10 nm. A tight process control of the layer thickness, layer density and microroughness of the growing film is required. We deposited silicon oxide on silicon wafers, float glass and superpolished quartz substrates. In a remote plasma enhanced CVD process, we used tetraethylorthosilicate (TEOS, Si(OC2H5)(4)) as precursor. Films with a thickness of some 10 nm were produced at different deposition parameters and characterized by in-situ soft X-ray reflectivity, hard X-ray diffraction and auger electron spectroscopy. Best results could be found for the deposition using TEOS in oxygen plasma. In case Of SiO2 layers deposited on standard glass substrates signifcant roughness smoothing was obtained

Role of exosite binding modulators in the inhibition of Fxa by TFPI

SummaryTissue factor pathway inhibitor (TFPI) down-regulates the extrinsic coagulation pathway by inhibiting FXa and FVIIa. Both TFPI and FXa interact with several plasma proteins (e. g. prothrombin, FV/FVa, protein S) and non-proteinaceous compounds (e. g. phospholipids, heparin). It was our aim to investigate effects of ligands that bind to FXa and TFPI on FXa inhibition by full-length TFPI (designated TFPI) and truncated TFPI (TFPI1-150). Inhibition of FXa by TFPI and TFPI1-150 and effects of phospholipids, heparin, prothrombin, FV, FVa, and protein S thereon was quantified from progress curves of conversion of the FXa-specific chromogenic substrate CS11-(65). Low concentrations negatively charged phospholipids (~10 μM) already maximally stimulated (up to 5- to 6-fold) FXa inhibition by TFPI. Unfractionated heparin at concentrations (0.2–1 U/ml) enhanced FXa inhibition by TFPI ~8-fold, but impaired inhibition at concentrations &gt; 1 U/ml. Physiological protein S and FV concentrations both enhanced FXa inhibition by TFPI 2- to 3-fold. In contrast, thrombin-activated FV (FVa) impaired the ability of TFPI to inhibit FXa. FXa inhibition by TFPI1–150 was not affected by FV, FVa, protein S, phospholipids and heparin. TFPI potently inhibited FXa-catalysed prothrombin activation in the absence of FVa, but hardly inhibited prothrombin activation in the presence of thrombin-activated FVa. In conclusion, physiological concentrations TFPI (0.25–0.5 nM TFPI) inhibit FXa with a t1/2 between 3–15 minutes. Direct FXa inhibition by TFPI is modulated by physiological concentrations prothrombin, FV, FVa, protein S, phospholipids and heparin indicating the importance of these modulators for the in vivo anticoagulant activity of TFPI.</jats:p

TFPI Expresses Anticoagulant Activity Independent Of TF-FVIIa

Abstract Tissue factor pathway inhibitor (TFPI) is a Kunitz-type serine protease inhibitor that down-regulates the extrinsic coagulation pathway by inhibiting the tissue factor-factor VIIa complex (TF-FVIIa). Inhibition of TF-FVIIa by TFPI is greatly enhanced by FXa. In order to inhibit TF-FVIIa, TFPI first binds to and inhibits Factor Xa (FXa) thus forming a binary TFPI-FXa complex in a reaction that is stimulated by protein S. The TFPI-FXa complex subsequently forms a quaternary complex with TF-FVIIa and blocks the initiation of coagulation. Although TFPI can directly inhibit FXa, this inhibition is generally considered to be of limited physiological significance because the plasma TFPI concentration (0.25-0.5 nM) is several orders of magnitude lower than the plasma concentration of other FXa inhibitors e.g. antithrombin (AT = 2.5-5 μM). We investigated whether TFPI expresses anticoagulant activity independent of TF-FVIIa i.e. to test whether direct inhibition of FXa by TFPI contributes to the down-regulation of coagulation. In model systems, the inhibition of FXa by TFPI and AT was determined in the presence of calcium chloride, phospholipids and protein S using a chromogenic substrate to monitor FXa activity. FXa inhibition by TFPI in plasma was determined by measuring thrombin generation curves triggered with FXa, with the FXa activator from Russell’s viper venom (RVV-X) and with FXIa or FIXa in normal pooled plasma. These experiments were performed in the presence of a cocktail of anti TF/anti FVIIa antibodies to inhibit any contribution of traces of TF that might be present in plasma to initiate coagulation. The TF-independent contributions of TFPI and/or protein S to the down-regulation of thrombin generation were quantified 1) after neutralization of TFPI and protein S present in plasma with an anti-TFPI antibody cocktail or anti-protein S antibodies and 2) via TFPI and protein S titrations in TFPI- and in protein S-depleted plasma. In model systems containing purified proteins, physiological concentrations TFPI (0.25 nM) appeared to be more effective in FXa inhibition (t1/2 = 2.5 min) than physiological concentrations AT (2.5 μM) which inhibited FXa with t1/2 = 3.2 min. Both anti-TFPI and anti-protein S antibodies enhanced thrombin generation that was triggered in plasma with RVV-X, FXa, FIXa or FXIa. Depending on the trigger and trigger concentration used anti-TFPI and anti-protein S antibodies decreased the lag time and/or increased the peak height of thrombin generation. At high trigger concentrations neither anti-TFPI nor anti-protein S antibodies enhanced thrombin generation. TFPI and protein S titrations in TFPI- and protein S-depleted plasma in which thrombin formation was initiated with triggers other than TF confirmed that both TFPI and protein S express TF-independent anticoagulant activity. TFPI titrations in protein S-depleted plasma triggered with RVV-X or FXIa showed that the TF-independent anticoagulant activity of TFPI was greatly reduced in the absence of protein S. Supplementation of the protein S-depleted plasma with protein S restored the anticoagulant effect of TFPI. We demonstrated that TFPI, despite its low plasma concentration, expresses anticoagulant activity in the absence of TF. Kinetic experiments in model systems at plasma TFPI concentrations show that direct inhibition of FXa by TFPI can account for the TF-independent anticoagulant effect of TFPI on thrombin generation. Blocking the anticoagulant activity of protein S with anti-protein S antibodies also enhances thrombin generation with triggers other than TF. The fact that neutralization of TFPI and of protein S with specific antibodies resulted in a similar stimulation of thrombin generation suggests that TFPI is strongly dependent on the presence of protein S for expression of TF-independent anticoagulant activity in plasma. The ability of TFPI to inhibit thrombin generation initiated via the intrinsic coagulation pathway is an important observation particularly in the light of recent reports which indicate that the intrinsic coagulation pathway plays a relevant role in thrombus formation and in cardiovascular disease. Disclosures: Rosing: Baxter Innovations GmbH, Vienna, Austria: Consultancy, Research Funding. Hartmann:Baxter Innovations GmbH, Vienna, Austria: Employment. Scheiflinger:Baxter Innovations GmbH, Vienna, Austria: Employment. Dockal:Baxter Innovations GmbH, Vienna, Austria: Employment. </jats:sec